diff options
| -rw-r--r-- | color.c | 71 | ||||
| -rw-r--r-- | graphics.h | 2 |
2 files changed, 73 insertions, 0 deletions
@@ -147,3 +147,74 @@ rgba2xrgb(ulong c) return (c & 0xFF)<<24|(c>>24 & 0xFF)<<16| (c>>16 & 0xFF)<<8|(c>>8 & 0xFF); } + + +/* tone mapping */ + +/* + * simplified ACES filmic tone mapping curve by Krzysztof Narkowicz + * https://knarkowicz.wordpress.com/2016/01/06/aces-filmic-tone-mapping-curve/ + */ +static double +_aces(double value) +{ + double a = 2.51; + double b = 0.03; + double c = 2.43; + double d = 0.59; + double e = 0.14; + value = (value * (a * value + b)) / (value * (c * value + d) + e); + return fclamp(value, 0, 1); +} + +Color +aces(Color c) +{ + c.r = _aces(c.r); + c.g = _aces(c.g); + c.b = _aces(c.b); + return c; +} + +static double +RRTAndODTFit(double v) +{ + double a = v * (v + 0.0245786f) - 0.000090537f; + double b = v * (0.983729f * v + 0.4329510f) + 0.238081f; + return a / b; +} + +/* + * a better ACES curve fit by Stephen Hill (@self_shadow) + * https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl + */ +Color +aces2(Color c) +{ + /* sRGB → XYZ → D65_2_D60 → AP1 → RRT_SAT */ + Matrix3 ACESInputMat = { + 0.59719, 0.35458, 0.04823, 0, + 0.07600, 0.90834, 0.01566, 0, + 0.02840, 0.13383, 0.83777, 0, + 0, 0, 0, 1, + }; + /* ODT_SAT → XYZ → D60_2_D65 → sRGB */ + Matrix3 ACESOutputMat = { + 1.60475, -0.53108, -0.07367, 0, + -0.10208, 1.10813, -0.00605, 0, + -0.00327, -0.07276, 1.07602, 0, + 0, 0, 0, 1, + }; + + c = xform3(c, ACESInputMat); + /* Apply RRT and ODT */ + c.r = RRTAndODTFit(c.r); + c.g = RRTAndODTFit(c.g); + c.b = RRTAndODTFit(c.b); + + c = xform3(c, ACESOutputMat); + c.r = fclamp(c.r, 0, 1); + c.g = fclamp(c.g, 0, 1); + c.b = fclamp(c.b, 0, 1); + return c; +} @@ -418,6 +418,8 @@ Memimage *dupmemimage(Memimage*); Color srgb2linear(Color); Color linear2srgb(Color); ulong rgba2xrgb(ulong); +Color aces(Color); +Color aces2(Color); /* shadeop */ double sign(double); |